基于中国CRA-40再分析数据计算大气去混频模型及其质量评估

Computation and Assessment Concerning Atmospheric Dealiasing Models Using CRA-40 Reanalysis Dataset

  • 摘要: 大气与海洋非潮汐高频质量变化是时变重力场反演过程中需要精确建模并提前扣除的重要误差来源,随着我国重力卫星计划的推进,实现这一地球重力场背景力模型的国产化具有重要意义。CRA-40为中国第一代大气再分析产品,对其表面压力与温度数据的比较结果表明其数据质量与第三代全球再分析产品相当。以CRA-40为输入数据计算了一套大气去混频模型CRA-40-AD,从球谐系数、KBRR残差、反演时变重力场三个层面对其做质量评估。评估结果表明,CRA-40-AD与GFZ AOD1B RL06(RL06)在谱域以及时域相关性较好,与RL06的谱域差距在约20阶之后小于GRACE模拟精度;CRA-40-AD与RL06的星间距离变率残差RMS差异不足20 nm/s,满足当前GRACE K波段测距系统的精度;CRA-40-AD与RL06反演时变重力场的大地水准面高阶方差曲线的数值差异在0~0.6 mm之间,满足地球重力场1 mm的大地水准面精度要求。对CRA-40大气再分析计算大气去混频模型的多方验证表明CRA-40-AD模型满足当前时变重力场反演的要求,有望实现大气去混频产品的完全国产化。

     

    Abstract: Objectives: Atmospheric and oceanic non-tidal high-frequency mass variations constitute a primary source of error that need to be accurately modeled and removed before the process of time-variable gravity field inversion. The advancement of China's gravity satellite mission makes achieving the domestic production of the background force model for the earth's gravity field highly meaningful. Methods: CRA-40 is China's first generation of reanalysis products. The evaluation of surface pressure and temperature illustrates that its quality is comparable to the third generation of global reanalysis on the basis of the comparisons we perform. A set of atmospheric dealiasing models, CRA-40-AD, are calculated by using CRA-40 as input data. To investigate the applicability of employing CRA-40 reanalysis to calculate atmospheric dealiasing model, the validation of resulted models was carried out from three aspects including spherical harmonic coefficients, KBRR residuals and geoid heights derived from time-variable gravity field models. Results: The results of the evaluations indicate that CRA40-AD exhibit a strong correlation with GFZ AOD1B RL06(RL06)in both spectral and time domains. The differences between CRA40-AD and RL06 in spectral domain are smaller than the GRACE simulation accuracy after 20 orders. The RMS differences of the KBRR residuals between CRA-40-AD and RL06 are below 20 nm/s, which conforms to the accuracy of GRACE K-band ranging system. The differences in geoid degree between CRA-40-AD and RL06 range from 0 to 0.6 mm, which satisfies the 1 mm geoid accuracy. Conclusions: Consequently, CRA-40 has been shown to have the potential to be used in atmospheric dealiasing models, making the fully localization of atmospheric dealiasing products promising to achieve.

     

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